I don't care to go to Las Vegas, and I don't care to go to DEFCON, but you can easily fly from anywhere to Las Vegas, any time of year. (Subject to US visa issues, of course)
Others have said August is off-peak for Vegas (perhaps because of the weather), which means its a good time for a conference as space should be less expensive.
Others have said August is off-peak for Vegas (perhaps because of the weather), which means its a good time for a conference as space should be less expensive.